#include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#include<cmath>
#include<map>
#include<set>
#include<cstdio>
#include<algorithm>
#define debug(a) cout<<#a<<"="<<a<<endl;
using namespace std;
const int maxn=2e5+1000;
typedef long long LL;
inline LL read(){LL x=0,f=1;char ch=getchar();	while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
return x*f;}
int main(void){
   	cin.tie(0);std::ios::sync_with_stdio(false);
    LL t;cin>>t;
    while(t--){
        LL n,m;cin>>n>>m;
        LL ans=0;
        m++;
        for(LL k=30;k>=0&&n<m;k--){
            if( (n>>k&1) == ( m>>k&1 ) ) continue;
            else if( ( ( (n>>k)&1 )==0 ) && (m>>k)&1==1 ){
                ans|=(1<<k);
                n|=(1<<k);
            }
        }
        cout<<ans<<"\n";
    }
   	return 0;
}
